Displaying publications 621 - 640 of 10373 in total

Abstract:
Sort:
  1. Synthesis, β-glucuronidase inhibition and molecular docking studies of cyano-substituted bisindole hydrazone hybrids
    Abid O, Imran S, Taha M, Ismail NH, Jamil W, Kashif SM, et al.
    Mol Divers, 2021 May;25(2):995-1009.
    PMID: 32301032 DOI: 10.1007/s11030-020-10084-4
    The β-glucuronidase, a lysosomal enzyme, catalyzes the cleavage of glucuronosyl-O-bonds. Its inhibitors play a significant role in different medicinal therapies as they cause a decrease in carcinogen-induced colonic tumors by reducing the level of toxic substances present in the intestine. Among those inhibitors, bisindole derivatives had displayed promising β-glucuronidase inhibition activity. In the current study, hydrazone derivatives of bisindolymethane (1-30) were synthesized and evaluated for in vitro β-glucuronidase inhibitory activity. Twenty-eight analogs demonstrated better activity (IC50 = 0.50-46.5 µM) than standard D-saccharic acid 1,4-lactone (IC50 = 48.4 ± 1.25 µM). Compounds with hydroxyl group like 6 (0.60 ± 0.01 µM), 20 (1.50 ± 0.10 µM) and 25 (0.50 ± 0.01 µM) exhibited the most potent inhibitory activity, followed by analogs with fluorine 21 (3.50 ± 0.10 µM) and chlorine 23 (8.20 ± 0.20 µM) substituents. The presence of hydroxyl group at the aromatic side chain was observed as the main contributing factor in the inhibitory potential. From the docking studies, it was predicted that the active compounds can fit properly in the binding groove of the β-glucuronidase and displayed significant binding interactions with essential residues.
    Matched MeSH terms: Glucuronidase/chemistry
  2. Highly Efficient Deacidification of High-Acid Rice Bran Oil Using Methanol as a Novel Acyl Acceptor
    Li D, Faiza M, Ali S, Wang W, Tan CP, Yang B, et al.
    Appl Biochem Biotechnol, 2018 Apr;184(4):1061-1072.
    PMID: 28948493 DOI: 10.1007/s12010-017-2594-1
    A highly efficient process for reducing the fatty acid (FA) content of high-acid rice bran oil (RBO) was developed by immobilized partial glycerides-selective lipase SMG1-F278N-catalyzed esterification/transesterification using methanol as a novel acyl acceptor. Molecular docking simulation indicated that methanol was much closer to the catalytic serine (Ser-171) compared with ethanol and glycerol, which might be one of the reasons for its high efficiency in the deacidification of high-acid RBO. Additionally, the reaction parameters were optimized to minimize the FA content of high-acid RBO. Under the optimal conditions (substrate molar ratio of methanol to FAs of 1.8:1, enzyme loading of 40 U/g, and at 30 °C), FA content decreased from 25.14 to 0.03% after 6 h of reaction. Immobilized SMG1-F278N exhibited excellent methanol tolerance and retained almost 100% of its initial activity after being used for ten batches. After purification by molecular distillation, the final product contained 97.86% triacylglycerol, 2.10% diacylglycerol, and 0.04% FA. The acid value of the final product was 0.09 mg KOH/g, which reached the grade one standard of edible oil. Overall, methanol was a superior acyl acceptor for the deacidification of high-acid RBO and the high reusability of immobilized SMG1-F278N indicates an economically attractive process.
    Matched MeSH terms: Methanol/chemistry*
  3. Fulltext Ceramicines M-P from Chisocheton ceramicus: isolation and structure-activity relationship study
    Nugroho AE, Hashimoto A, Wong CP, Yokoe H, Tsubuki M, Kaneda T, et al.
    J Nat Med, 2018 Jan;72(1):64-72.
    PMID: 28822030 DOI: 10.1007/s11418-017-1109-2
    Ceramicines are a series of limonoids which were isolated from the bark of Malaysian Chisocheton ceramicus (Meliaceae) and show various biological activities. Ceramicine B, in particular, has been reported to show a strong lipid droplet accumulation (LDA) inhibitory activity on a mouse pre-adipocyte cell line (MC3T3-G2/PA6). With the purpose of discovering compounds with stronger activity than ceramicine B, we further investigated the constituents of C. ceramicus. As a result, from the bark of C. ceramicus four new ceramicines (ceramicines M-P, 1-4) were isolated, and their structures were determined on the basis of NMR and mass spectroscopic analyses in combination with NMR chemical shift calculations. LDA inhibitory activity of 1-4 was evaluated. Compounds 1-3 showed LDA inhibitory activity, and 3 showed better selectivity than ceramicine B while showing activity at the same order of magnitude as ceramicine B. Since 3, which possess a carbonyl group at C-7, showed better selectivity than 5, which possess a 7α-OH group, while showing activity at the same order of magnitude as 5, we also investigated the effect of the substituent at C-7 by synthesizing several derivatives and evaluating their LDA inhibitory activity. Accordingly, we confirmed the importance of the presence of a 7α-OH group to the LDA inhibitory activity.
    Matched MeSH terms: Limonins/chemistry*
  4. New crosslinked-chitosan graft poly(N-vinyl-2-pyrrolidone) for the removal of Cu(II) ions from aqueous solutions
    Sutirman ZA, Sanagi MM, Abd Karim J, Abu Naim A, Wan Ibrahim WA
    Int J Biol Macromol, 2018 Feb;107(Pt A):891-897.
    PMID: 28935540 DOI: 10.1016/j.ijbiomac.2017.09.061
    Crosslinked chitosan beads were grafted with N-vinyl-2-pyrrolidone (NVP) using ammonium persulfate (APS) as free radical initiator. Important variables on graft copolymerization such as temperature, reaction time, concentration of initiator and concentration of monomer were optimized. The results revealed optimum conditions for maximum grafting of NVP on 1g crosslinked chitosan as follows: reaction temperature, 60°C; reaction time, 2h and concentrations of APS and NVP of 2.63×10-1M and 26.99×10-1M, respectively. The modified chitosan beads were characterized by FTIR spectroscopy, 13C NMR, SEM and BET to provide evidence of successful crosslinking and grafting reactions. The resulting material (cts(x)-g-PNVP) was evaluated as adsorbent for the removal of Cu(II) ions from aqueous solutions in a batch experiment. The Langmuir and Freundlich adsorption models were also applied to describe the equilibrium isotherms. The results showed that the adsorption of the copper ions onto the beads agreed well with Langmuir model with the maximum capacity (qmax) of 122mgg-1.
    Matched MeSH terms: Copper/chemistry*; Cross-Linking Reagents/chemistry; Ions/chemistry; Pyrrolidinones/chemistry; Water/chemistry; Water Pollutants, Chemical/chemistry*; Chitosan/chemistry*
  5. Effects of Environmental Stresses and in Vitro Digestion on the Release of Tocotrienols Encapsulated Within Chitosan-Alginate Microcapsules
    Tan PY, Tan TB, Chang HW, Tey BT, Chan ES, Lai OM, et al.
    J Agric Food Chem, 2017 Dec 06;65(48):10651-10657.
    PMID: 29124932 DOI: 10.1021/acs.jafc.7b03521
    Considering the health benefits of tocotrienols, continuous works have been done on the encapsulation and delivery of these compounds. In this study, we encapsulated tocotrienols in chitosan-alginate microcapsules and evaluated their release profile. Generally, these tocotrienols microcapsules (TM) displayed high thermal stability. When subjected to pH adjustments (pH 1-9), we observed that the release of tocotrienols was the highest (33.78 ± 0.18%) under basic conditions. The TM were also unstable against the effect of ionic strength, with a high release (70.73 ± 0.04%) of tocotrienols even at a low sodium chloride concentration (50 mM). As for the individual isomers, δ-tocotrienol was the most sensitive to pH and ionic strength. In contrast, β-/γ-tocotrienols were the most ionic-stable isomers but more responsive toward thermal treatment. Simulated gastrointestinal model showed that the chitosan-alginate-based TM could be used to retain tocotrienols in the gastric and subsequently release them in the intestines for possible absorption.
    Matched MeSH terms: Alginates/chemistry*; Capsules/chemistry*; Drug Carriers/chemistry*; Hexuronic Acids/chemistry; Glucuronic Acid/chemistry; Tocotrienols/chemistry*; Chitosan/chemistry*
  6. Rhizomucor miehei lipase immobilized on reinforced chitosan-chitin nanowhiskers support for synthesis of eugenyl benzoate
    Abdul Manan FM, Attan N, Widodo N, Aboul-Enein HY, Wahab RA
    Prep Biochem Biotechnol, 2018 Jan 02;48(1):92-102.
    PMID: 29194017 DOI: 10.1080/10826068.2017.1405021
    An alternative environmentally benign support was prepared from chitosan-chitin nanowhiskers (CS/CNWs) for covalent immobilization of Rhizomucor miehei lipase (RML) to increase the operational stability and recyclability of RML in synthesizing eugenyl benzoate. The CS/CNWs support and RML-CS/CNWs were characterized using X-ray diffraction, fluorescent microscopy, and Fourier transform infrared spectroscopy. Efficiency of the RML-CS/CNWs was compared to the free RML to synthesize eugenyl benzoate for parameters: reaction temperature, stirring rate, reusability, and thermal stability. Under optimal experimental conditions (50°C, 250 rpm, catalyst loading 3 mg/mL), a twofold increase in yield of eugenyl benzoate was observed for RML-CS/CNWs as compared to free RML, with the former achieving maximum yield of the ester at 62.1% after 5 hr. Results demonstrated that the strategy adopted to prepare RML-CS/CNWs was useful, producing an improved and prospectively greener biocatalyst that supported a sustainable process to prepare eugenyl benzoate. Moreover, RML-CS/CNWs are biodegradable and perform esterification reactions under ambient conditions as compared to the less eco-friendly conventional acid catalyst. This research provides a facile and promising approach for improving activity of RML in which the resultant RML-CS/CNWs demonstrated good operational stability for up to eight successive esterification cycles to synthesize eugenyl benzoate.
    Matched MeSH terms: Benzoates/chemistry; Chitin/chemistry*; Enzymes, Immobilized/chemistry; Lipase/chemistry; Rhizomucor/chemistry; Chitosan/chemistry*; Nanostructures/chemistry
  7. Synthesis and evaluation on pH- and temperature-responsive chitosan-p(MAA-co-NIPAM) hydrogels
    Rasib SZM, Ahmad Z, Khan A, Akil HM, Othman MBH, Hamid ZAA, et al.
    Int J Biol Macromol, 2018 Mar;108:367-375.
    PMID: 29222015 DOI: 10.1016/j.ijbiomac.2017.12.021
    In this study, chitosan-poly(methacrylic acid-co-N-isopropylacrylamide) [chitosan-p(MAA-co-NIPAM)] hydrogels were synthesized by emulsion polymerization. In order to be used as a carrier for drug delivery systems, the hydrogels had to be biocompatible, biodegradable and multi-responsive. The polymerization was performed by copolymerize MAA and NIPAM with chitosan polymer to produce a chitosan-based hydrogel. Due to instability during synthesis and complexity of components to produce the hydrogel, further study at different times of reaction is important to observe the synthesis process, the effect of end product on swelling behaviour and the most important is to find the best way to control the hydrogel synthesis in order to have an optimal swelling behaviour for drug release application. Studied by using Fourier transform infra-red (FTIR) spectroscopy found that, the synthesized was successfully produced stable chitosan-based hydrogel with PNIPAM continuously covered the outer surface of hydrogel which influenced much on the stability during synthesis. The chitosan and PMAA increased the zeta potential of the hydrogel and the chitosan capable to control shrinkage above human body temperature. The chitosan-p(MAA-co-NIPAM) hydrogels also responses to pH and temperature thus improved the ability to performance as a drug carrier.
    Matched MeSH terms: Acrylic Resins/chemistry; Methacrylates/chemistry; Polymers/chemistry; Hydrogels/chemistry*; Chitosan/chemistry*; Chemistry Techniques, Synthetic*
  8. Fulltext Study of Cationic and Nonionic Mixed Micelles with NaBr and 3,5-Cl2C6H3CO2Na by Use of Probe Nucleophilic Reaction of Piperidine with Ionized Phenyl Salicylate
    Fagge II, Khalid K, Noh MAM, Yusof NSM, Zain SM, Khan MN
    J Oleo Sci, 2018 Jan 01;67(1):55-66.
    PMID: 29238023 DOI: 10.5650/jos.ess17033
    Behaviors of cationic and nonionic mixed micelles in the form of hexadecyltrimethylammonium bromide (HDABr) and hexadecyltrimethylammonium bromide-Polyethylene glycol hexadecyl ether (C16E20), in the presence of inert salts (NaBr and 3,5-dichlorosodium benzoate), by the use of reaction probe between Pp and ionized PhSH (Pp = piperidine and PhSH = phenyl salicylate), has been reported in this work. The values of RXBr (RXBr denotes ion exchange constants obtained in the presence of micelles of different structural features) or KXBr (KXBr denotes ion exchange constants obtained in the presence of micelles of the same structural features) for 3,5-Cl2C6H3CO2- were almost the same at three different [HDABr]T (0.006, 0.010 and 0.015 M). The average value of RXBr or KXBr determined, in the presence of pure HDABr micelles, using semi empirical kinetic (SEK) method appeared to be almost 2½-fold larger (RXBr or KXBr = 198) than that in the presence of mixed HDABr-C16E20 micelles (RXBr or KXBr = 78). Rheological measurements indicated the existence of wormlike/twisted micelles and vesicle at 0.015 M pure HDABr, various [3,5-Cl2C6H3CO2Na], and 25 and 35℃ whereas there were evidence of only spherical micelles in the presence of mixed HDABr-C16E20 ([HDABr]T = 0.015 M and [C16E20]T = 0.006 M) at both temperatures.
    Matched MeSH terms: Quaternary Ammonium Compounds/chemistry; Bromides/chemistry*; Cetomacrogol/chemistry; Chlorobenzoates/chemistry*; Piperidines/chemistry*; Salicylates/chemistry*; Sodium Compounds/chemistry*
  9. Influence of Solvent on the Drug-Loading Process of Amphiphilic Nanogel Star Polymers
    Carr AC, Piunova VA, Maarof H, Rice JE, Swope WC
    J Phys Chem B, 2018 05 31;122(21):5356-5367.
    PMID: 29385796 DOI: 10.1021/acs.jpcb.7b10539
    We present an all-atom molecular dynamics study of the effect of a range of organic solvents (dichloromethane, diethyl ether, toluene, methanol, dimethyl sulfoxide, and tetrahydrofuran) on the conformations of a nanogel star polymeric nanoparticle with solvophobic and solvophilic structural elements. These nanoparticles are of particular interest for drug delivery applications. As drug loading generally takes place in an organic solvent, this work serves to provide insight into the factors controlling the early steps of that process. Our work suggests that nanoparticle conformational structure is highly sensitive to the choice of solvent, providing avenues for further study as well as predictions for both computational and experimental explorations of the drug-loading process. Our findings suggest that when used in the drug-loading process, dichloromethane, tetrahydrofuran, and toluene allow for a more extensive and increased drug-loading into the interior of nanogel star polymers of the composition studied here. In contrast, methanol is more likely to support shallow or surface loading and, consequently, faster drug release rates. Finally, diethyl ether should not work in a formulation process since none of the regions of the nanogel star polymer appear to be sufficiently solvated by it.
    Matched MeSH terms: Drug Carriers/chemistry*; Pharmaceutical Preparations/chemistry*; Polyethylene Glycols/chemistry*; Polyethyleneimine/chemistry*; Polymers/chemistry*; Solvents/chemistry*; Nanoparticles/chemistry
  10. Effect of storage temperature on the stability of spray dried bacteriophage powders
    Leung SSY, Parumasivam T, Nguyen A, Gengenbach T, Carter EA, Carrigy NB, et al.
    Eur J Pharm Biopharm, 2018 Jun;127:213-222.
    PMID: 29486303 DOI: 10.1016/j.ejpb.2018.02.033
    This study aimed to assess the robustness of using a spray drying approach and formulation design in producing inhalable phage powders. Two types of Pseudomonas phages, PEV2 (Podovirus) and PEV40 (Myovirus) in two formulations containing different amounts of trehalose (70% and 60%) and leucine (30% and 40%) were studied. Most of the surface of the produced powders was found to be covered in crystalline leucine. The powders were stored at 4 °C and 20 °C under vacuum. The phage stability and in vitro aerosol performance of the phage powders were examined on the day of production and after 1, 3 and 12 months of storage. A minor titer loss during production was observed for both phages (0.2-0.8 log10 pfu/ml). The storage stability of the produced phage powders was found to be phage and formulation dependent. No further reduction in titer occurred for PEV2 powders stored at 4 °C across the study. The formulation containing 30% leucine maintained the viability of PEV2 at 20 °C, while the formulation containing 40% leucine gradually lost titer over time with a storage reduction of ∼0.9 log10 pfu/ml measured after 12 months. In comparison, the PEV40 phage powders generally had a ∼ 0.5 log10 pfu/ml loss upon storage regardless of temperature. When aerosolized, the total in vitro lung doses of PEV2 were of the order of 107 pfu, except the formulation containing 40% leucine stored at 20 °C which had a lower lung dose. The PEV40 powders also had lung doses of 106-107 pfu. The results demonstrate that spray dried Myoviridae and Podoviridae phage in a simple formulation of leucine and trehalose can be successfully stored for one year at 4 °C and 20 °C with vacuum packaging.
    Matched MeSH terms: Aerosols/chemistry; Bacteriophages/chemistry*; Chemistry, Pharmaceutical/methods; Excipients/chemistry; Powders/chemistry*; Trehalose/chemistry
  11. Fulltext One-Step Partially Purified Lipases (ScLipA and ScLipB) from Schizophyllum commune UTARA1 Obtained via Solid State Fermentation and Their Applications
    Kam YC, Woo KK, Ong LGA
    Molecules, 2017 Dec 08;22(12).
    PMID: 29292721 DOI: 10.3390/molecules22122106
    Lipases with unique characteristics are of value in industrial applications, especially those targeting cost-effectiveness and less downstream processes. The aims of this research were to: (i) optimize the fermentation parameters via solid state fermentation (SSF); and (ii) study the performance in hydrolysis and esterification processes of the one-step partially purified Schizophyllum commune UTARA1 lipases. Lipase was produced by cultivating S. commune UTARA1 on sugarcane bagasse (SB) with used cooking oil (UCO) via SSF and its production was optimized using Design-Expert® 7.0.0. Fractions 30% (ScLipA) and 70% (ScLipB) which contained high lipase activity were obtained by stepwise (NH₄)₂SO₄ precipitation. Crude fish oil, coconut oil and butter were used to investigate the lipase hydrolysis capabilities by a free glycerol assay. Results showed that ScLipA has affinities for long, medium and short chain triglycerides, as all the oils investigated were degraded, whereas ScLipB has affinities for long chain triglycerides as it only degrades crude fish oil. During esterification, ScLipA was able to synthesize trilaurin and triacetin. Conversely, ScLipB was specific towards the formation of 2-mono-olein and triacetin. From the results obtained, it was determined that ScLipA and ScLipB are sn-2 regioselective lipases. Hence, the one-step partial purification strategy proved to be feasible for partial purification of S. commune UTARA1 lipases that has potential use in industrial applications.
    Matched MeSH terms: Fish Oils/chemistry; Glycerol/chemistry; Lipase/chemistry*; Oleic Acids/chemistry; Plant Oils/chemistry; Triacetin/chemistry; Triglycerides/chemistry
  12. Thermal, mechanical, and physical properties of seaweed/sugar palm fibre reinforced thermoplastic sugar palm Starch/Agar hybrid composites
    Jumaidin R, Sapuan SM, Jawaid M, Ishak MR, Sahari J
    Int J Biol Macromol, 2017 Apr;97:606-615.
    PMID: 28109810 DOI: 10.1016/j.ijbiomac.2017.01.079
    The aim of this research is to investigate the effect of sugar palm fibre (SPF) on the mechanical, thermal and physical properties of seaweed/thermoplastic sugar palm starch agar (TPSA) composites. Hybridized seaweed/SPF filler at weight ratio of 25:75, 50:50 and 75:25 were prepared using TPSA as a matrix. Mechanical, thermal and physical properties of hybrid composites were carried out. Obtained results indicated that hybrid composites display improved tensile and flexural properties accompanied with lower impact resistance. The highest tensile (17.74MPa) and flexural strength (31.24MPa) was obtained from hybrid composite with 50:50 ratio of seaweed/SPF. Good fibre-matrix bonding was evident in the scanning electron microscopy (SEM) micrograph of the hybrid composites' tensile fracture. Fourier transform infrared spectroscopy (FT-IR) analysis showed increase in intermolecular hydrogen bonding following the addition of SPF. Thermal stability of hybrid composites was enhanced, indicated by a higher onset degradation temperature (259°C) for 25:75 seaweed/SPF composites than the individual seaweed composites (253°C). Water absorption, thickness swelling, water solubility, and soil burial tests showed higher water and biodegradation resistance of the hybrid composites. Overall, the hybridization of SPF with seaweed/TPSA composites enhances the properties of the biocomposites for short-life application; that is, disposable tray, plate, etc.
    Matched MeSH terms: Agar/chemistry*; Plastics/chemistry*; Seaweed/chemistry*; Soil/chemistry; Starch/chemistry*; Water/chemistry; Arecaceae/chemistry*
  13. Status of cosmetic safety in Malaysia market: Mercury contamination in selected skin whitening products
    Wan Mohamed Radzi CWJ, Nordin FNM
    J Cosmet Dermatol, 2022 Dec;21(12):6875-6882.
    PMID: 36181345 DOI: 10.1111/jocd.15429
    BACKGROUND: Concern on cosmetic safety has been a subject of interest in recent years and is commonly associated with the exposure of the consumers to chemicals and impurities such as mercury contamination. Moreover, cancellations of notified cosmetic products were recurrently being reported by the Malaysia authority, namely the National Pharmaceutical Regulatory Authority (NPRA). Among the cosmetic categories was skin whitening product, which is still in high demand whilst reported to cause health risks. Besides, low number of studies on cosmetic safety and mercury contamination were recorded in Malaysia. The lack of scientific evidence on the safety and risks of the ingredients used in cosmetic formulation is a major concern to many consumers.

    OBJECTIVE: The aim of this study was to identify the presence of mercury in skin whitening products, and to identify products containing mercury with the concentration exceeding the limitation of 1 ppm.

    METHODOLOGY: A total of 104 whitening products were selected from the market via random sampling technique. The mercury concentration was determined by accredited laboratory, and the results were later compared with the cosmetic guideline of Malaysia and the list of banned products issued by NPRA.

    RESULTS: A total of 51.9% (n = 54) whitening products were found registered under the NPRA Quest system and remaining 48.1% (n = 50) were non-registered products. None of the whitening products listed mercury as an ingredient, but laboratory analysis showed 15.4% (n = 16) of the products contained mercury with the concentration exceeding the maximum limit of 1 ppm. A total of 87.5% of the whitening products (14 out of 16) containing high mercury concentration were non-registered products which were not registered in NPRA Quest system. The exceeded concentration recorded ranged between 1.81 ppm and 838 123 ppm. Besides that, 50% (8 out of 16) of the products were found in the list of banned products issued by the NPRA of Malaysia.

    CONCLUSIONS: This study presents the status of cosmetic products, particularly the skin whitening products available in Malaysia market. Concern arises when some of the products were found to have presence of harmful substances such as mercury. Even though the presence of mercury in a cosmetic product can either be non-intentional or intentionally used by the manufacturer in the cosmetic formulation, the impact of the ingredient can cause health risk to the users.

    Matched MeSH terms: Skin/chemistry
  14. Valorization of nano-based lignocellulosic derivatives to procure commercially significant value-added products for biomedical applications
    As V, Kumar G, Dey N, Karunakaran R, K A, Patel AK, et al.
    Environ Res, 2023 Jan 01;216(Pt 2):114400.
    PMID: 36265604 DOI: 10.1016/j.envres.2022.114400
    Biowaste, produced from nature, is preferred to be a good source of carbon and ligninolytic machinery for many microorganisms. They are complex biopolymers composed of lignin, cellulose, and hemicellulose traces. This biomass can be depolymerized to its nano-dimensions to gain exceptional properties useful in the field of cosmetics, pharmaceuticals, high-strength materials, etc. Nano-sized biomass derivatives overcome the inherent drawbacks of the parent material and offer promises as a potential material for a wide range of applications with their unique traits such as low-toxicity, biocompatibility, biodegradability and environmentally friendly nature with versatility. This review focuses on the production of value-added products feasible from nanocellulose, nano lignin, and xylan nanoparticles which is quite a novel study of its kind. Dawn of nanotechnology has converted bio waste by-products (hemicellulose and lignin) into useful precursors for many commercial products. Nano-cellulose has been employed in the fields of electronics, cosmetics, drug delivery, scaffolds, fillers, packaging, and engineering structures. Xylan nanoparticles and nano lignin have numerous applications as stabilizers, additives, textiles, adhesives, emulsifiers, and prodrugs for many polyphenols with an encapsulation efficiency of 50%. This study will support the potential development of composites for emerging applications in all aspects of interest and open up novel paths for multifunctional biomaterials in nano-dimensions for cosmetic, drug carrier, and clinical applications.
    Matched MeSH terms: Cellulose/chemistry
  15. Performance evaluation of phosphonium based deep eutectic solvents coated cerium oxide nanoparticles for CO2 capture
    Ahmad T, Iqbal J, Bustam MA, Babar M, Tahir MB, Sagir M, et al.
    Environ Res, 2023 Apr 01;222:115314.
    PMID: 36738770 DOI: 10.1016/j.envres.2023.115314
    The critical challenge being faced by our current modern society on a global scale is to reduce the surging effects of climate change and global warming, being caused by anthropogenic emissions of CO2 in the environment. Present study reports the surface driven adsorption potential of deep eutectic solvents (DESs) surface functionalized cerium oxide nanoparticles (CeNPs) for low pressure CO2 separation. The phosphonium based DESs were prepared using tetra butyl phosphoniumbromide as hydrogen bond acceptor (HBA) and 6 acids as hydrogen bond donors (HBDs). The as-developed DESs were characterized and employed for the surface functionalization of CeNPs with their subsequent utilization in adsorption-based CO2 adsorption. The synthesis of as-prepared DESs was confirmed through FTIR measurements and absence of precipitates, revealed through visual observations. It was found that DES6 surface functionalized CeNPs demonstrated 27% higher adsorption performance for CO2 capturing. On the contrary, DES3 coated CeNPs exhibited the least adsorption progress for CO2 separation. The higher adsorption performance associated with DES6 coated CeNPs was due to enhanced surface affinity with CO2 molecules that must have facilitated the mass transport characteristics and resulted an enhancement in CO2 adsorption performance. Carboxylic groups could have generated an electric field inside the pores to attract more polarizable adsorbates including CO2, are responsible for the relatively high values of CO2 adsorption. The quadruple movement of the CO2 molecules with the electron-deficient and pluralizable nature led to the enhancement of the interactive forces between the CO2 molecules and the CeNPs decorated with the carboxylic group hydrogen bond donor rich DES. The current findings may disclose the new research horizons and theoretical guidance for reduction in the environmental effects associated with uncontrolled CO2 emission via employing DES surface coated potential CeNPs.
    Matched MeSH terms: Solvents/chemistry
  16. Computational docking of L-arginine and its structural analogues to C-terminal domain of Escherichia coli arginine repressor protein (ArgRc)
    Kueh R, Rahman NA, Merican AF
    J Mol Model, 2003 Apr;9(2):88-98.
    PMID: 12707802
    The arginine repressor (ArgR) of Escherichia coli binds to six L-arginine molecules that act as its co-repressor in order to bind to DNA. The binding of L-arginine molecules as well as its structural analogues is compared by means of computational docking. A grid-based energy evaluation method combined with a Monte Carlo simulated annealing process was used in the automated docking. For all ligands, the docking procedure proposed more than one binding site in the C-terminal domain of ArgR (ArgRc). Interaction patterns of ArgRc with L-arginine were also observed for L-canavanine and L-citrulline. L-lysine and L-homoarginine, on the other hand, were shown to bind poorly at the binding site. Figure A general overview of the sites found from docking the various ligands into ArgRc ( grey ribbons). Red coloured sticks: residues in binding site H that was selected for docking
    Matched MeSH terms: Arginine/chemistry*; Canavanine/chemistry; Citrulline/chemistry; Homoarginine/chemistry; Lysine/chemistry; Repressor Proteins/chemistry*; Escherichia coli Proteins/chemistry*
  17. Polyneurines A-H, iboga alkaloids from Tabernaemontana polyneura
    Tang SY, Tan CH, Sim KS, Yong KT, Lim KH, Low YY, et al.
    Phytochemistry, 2023 Apr;208:113587.
    PMID: 36646163 DOI: 10.1016/j.phytochem.2023.113587
    Eight undescribed iboga alkaloids, polyneurines A-H, were isolated from the bark of Tabernaemontana polyneura. The structures of these alkaloids were established by interpretation of the MS and NMR data, while the configurations were determined using GIAO NMR calculations and DP4+ probability analysis, TDDFT-ECD method, or X-ray diffraction analysis. Polyneurine A possesses a γ-lactone unit embedded within the iboga skeleton, while polyneurines D and E incorporate a formylmethyl moiety at C-3 of the iboga skeleton. Biosynthetic pathways towards the formation of polyneurines A, C, D, and E were proposed.
    Matched MeSH terms: Indole Alkaloids/chemistry
  18. Surface analysis and thermal behavior of the functionalized cellulose by glutaric anhydride through a solvent-free and catalyst-free process
    Fahim H, Motamedzadegan A, Farahmandfar R, Khaligh NG
    Int J Biol Macromol, 2023 Mar 31;232:123268.
    PMID: 36646345 DOI: 10.1016/j.ijbiomac.2023.123268
    According to the 12 principles of green chemistry, surface functionalization was performed using glutaric anhydride under solvent-free and catalyst-free conditions. FTIR spectra and DS analyses demonstrated the functionalization of HCl-hydrolyzed cellulose. The influence of two parameters, i.e., the glutaric anhydride concentration and the reaction time, on the functionalization of HCl-hydrolyzed cellulose was investigated. Protocol efficiency was studied by a degree of substitution (DS). It was found that higher concentrations of glutaric anhydride cause an enhancement of DS to 0.75 and 0.87 for GA3-12 and GA9-12, respectively. In addition, the longer reaction time increased zeta potential from -12.2 ± 1.7 for G9-6 to -34.57 ± 2.2 for GA9-12. Morphology analysis by SEM showed a decrease in fiber length for the functionalized cellulose. DSC profiles confirmed dehydration at a range of 17 to 134 °C. A glass transition was revealed at -30 to -20 °C for all studied samples. The fusion, the depolymerization of cellulose chains, the cleavage of glycosidic linkages, and the decomposition of the crystalline parts of cellulose occur at 195 to 374 °C. Therefore, an efficient and greener process was developed to functionalize the HCl-hydrolyzed cellulose by glutaric anhydride, a safe and non-toxic anhydride, in the absence of the solvent and catalyst.
    Matched MeSH terms: Solvents/chemistry
  19. Knotting terminal ends of mutant T1 lipase with disulfide bond improved structure rigidity and stability
    Hamdan SH, Maiangwa J, Nezhad NG, Ali MSM, Normi YM, Shariff FM, et al.
    Appl Microbiol Biotechnol, 2023 Mar;107(5-6):1673-1686.
    PMID: 36752811 DOI: 10.1007/s00253-023-12396-5
    Lipase biocatalysts offer unique properties which are often impaired by low thermal and methanol stability. In this study, the rational design was employed to engineer a disulfide bond in the protein structure of Geobacillus zalihae T1 lipase in order to improve its stability. The selection of targeted disulfide bond sites was based on analysis of protein spatial configuration and change of Gibbs free energy. Two mutation points (S2C and A384C) were generated to rigidify the N-terminal and C-terminal regions of T1 lipase. The results showed the mutant 2DC lipase improved methanol stability from 35 to 40% (v/v) after 30 min of pre-incubation. Enhancement in thermostability for the mutant 2DC lipase at 70 °C and 75 °C showed higher half-life at 70 °C and 75 °C for 30 min and 52 min, respectively. The mutant 2DC lipase maintained the same optimum temperature (70 °C) as T1 lipase, while thermally induced unfolding showed the mutant maintained higher rigidity. The kcat/Km values demonstrated a relatively small difference between the T1 lipase (WT) and 2DC lipase (mutant). The kcat/Km (s-1 mM-1) of the T1 and 2DC showed values of 13,043 ± 224 and 13,047 ± 312, respectively. X-ray diffraction of 2DC lipase crystal structure with a resolution of 2.04 Å revealed that the introduced single disulfide bond did not lower initial structural interactions within the residues. Enhanced methanol and thermal stability are suggested to be strongly related to the newly disulfide bridge formation and the enhanced compactness and rigidity of the mutant structure. KEY POINTS: • Protein engineering via rational design revealed relative improved enzymatic performance. • The presence of disulfide bond impacts on the rigidity and structural function of proteins. • X-ray crystallography reveals structural changes accompanying protein modification.
    Matched MeSH terms: Disulfides/chemistry
  20. Fulltext Ruthenium(II) Polypyridyl Complexes as FRET Donors: Structure- and Sequence-Selective DNA-Binding and Anticancer Properties
    Elgar CE, Yusoh NA, Tiley PR, Kolozsvári N, Bennett LG, Gamble A, et al.
    J Am Chem Soc, 2023 Jan 18;145(2):1236-1246.
    PMID: 36607895 DOI: 10.1021/jacs.2c11111
    Ruthenium(II) polypyridyl complexes (RPCs) that emit from metal-to-ligand charge transfer (MLCT) states have been developed as DNA probes and are being examined as potential anticancer agents. Here, we report that MLCT-emissive RPCs that bind DNA undergo Förster resonance energy transfer (FRET) with Cy5.5-labeled DNA, forming mega-Stokes shift FRET pairs. Based on this discovery, we developed a simple and rapid FRET binding assay to examine DNA-binding interactions of RPCs with diverse photophysical properties, including non-"light switch" complexes [Ru(dppz)2(5,5'dmb)]2+ and [Ru(PIP)2(5,5'dmb)]2+ (dppz = dipyridophenazine, 5,5'dmb = 5,5'-dimethyl-2,2'-bipyridine, PIP = 2-phenyl-imidazo[4,5-f][1,10]phenanthroline). Binding affinities toward duplex, G-quadruplex, three-way junction, and mismatch DNA were determined, and derived FRET donor-acceptor proximities provide information on potential binding sites. Molecules characterized by this method demonstrate encouraging anticancer properties, including synergy with the PARP inhibitor Olaparib, and mechanistic studies indicate that [Ru(PIP)2(5,5'dmb)]2+ acts to block DNA replication fork progression.
    Matched MeSH terms: DNA/chemistry
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links